Duplicator fluid



Patented Apr. 2, 1935 DUPLICATOR FLUID Philip 'A. Shillenn, Camden, N.J., assignor to Radio Corporation of America, a corporation of DelawareNo Drawing. Application February 28, 1934,

Serial No. 713,419

11 Claims.

wax or other suitable surface in so-called duplicator or print transfermachines.

Such machines' are used to a great extent when it is desired to producea large number of duplicate copies of some subject matter originallyprinted with a typewriter, for example.

The machine is prepared in somewhat the following manner:

A special duplicating or carbon paper the transfer surface of whichcomprises a coating or layer of suitable waxes and dyes is placedagainst a clean sheet of any standard or. suitable typewriting paper inthe usual manner. As the typist prints the desired subject matter, animpression ,ismade upon the clean paper which backs up the specialcarbon paper, and this impression is transferred, by pressure, to agelatin or the like surface in the duplicator machine, the said gelatinsurface then being adapted to act as a master copy from which the largenumber of duplicates are to be formed. The impressions on the master arethen transferred to clean sheets first by wetting either the gelatinmaster or the clean sheets with a suitable solvent for the dye and waximpression and then by bringing the sheets into contact with thegelatine master under pressure. It is this solvent which is referred toherein as the duplicator or transfer fluid. For the most eflicienttransfer action, it is essential that the transfer fluid not only 'be agood solvent, but it must also have good penetrative qualities so as tobe able to penetrate the impression on the master and dissolve off asufficient quantity of the dye to make a satisfactory impression on theclean paper. Although a number of transfer fluids are available on themarket, they are objectionable for any one or more of several reasonsamong which are (1) insufiicient penetrative ability, (2) poorevaporainvention is to provide an improved duplicator fluid which isespecially applicable to transfer mediums compounded with waxes.

. Still another object of my invention is to provide an improvedduplicator fluid which will not only have good penetrative andevaporative qualities as well as good solvent action, but which will benon-toxic in its effect upon the human system.

A further object of my invention is to provide an improved duplicatorfluid which will have the characteristic of being able to simultaneouslydissolve Waxes and water or alcohol soluble dyes. 10

Still a further object of my invention is to provide an improvedduplicator fluid which will reduce blurring, creeping and smearing oftransferred copies whereby clean, clear copies may be obtained. I

Another object of my invention is to provide an improved duplicatorfluid which is not only highly efflcient in actionbut which iseconomical in cost.

In accordance with my invention, I compound my improved duplicator fluidfrom ethyl alcohol, ethylene glycol mono-ethyl ether and water in suchproportions as to render each ingredient most effective for theparticular purpose for which it is included.

The novel features of my invention are set forth with particularity inthe appended claims. However, the invention itself will best beunderstood from the following description of a specific embodiment: 30

Among the duplicator or transfer fluids heretofore available are somewhich employ methyl alcohol'as the dye solvent. Efiorts have been madeto substitute ethyl alcohol for the toxic methyl alcohol so as to renderthe transfer fluid non-toxic, but a mere substitution of ethyl alcoholfor methyl alcohol results in a product which lacks sufficientpenetrative properties. For this .reason, methyl alcohol has beenretained despite its toxic action.

In my experiments with transfer fluids of this type, I have found thatthe amount of water present has a great influence upon the solvent andpenetrative qualities of the fluid. I have found that a fluid in whichethyl alcohol has been substituted for methyl alcohol can be made even.more eflicient in its action than the methyl alcohol containing fluid bythe introduction of a substantially greater amount of water than haspreviously been used in any of the duplicator fluids withwhich I amfamiliar. Apparently the water content is very important in determiningthe solvent and penetrative qualities of the transfer fluid, and, by a.proper proportloning of the ingredients, a fluid having optimumcharacteristics 55 may be obtained. Thus, the toxic methyl alcohol maybe eliminated and a fluid obtained which is highly eflicient in actionas well as being free from the objection of toxicity.

As an example of what I have found satisfactory, the following formulais cited:

Denatured ethyl alcohol 25% by volume Ethylene glycol mono-ethyl ether(known commercially as cellosolve) 60% by volume Water by volume Theingredients are mixed in the proportions indicated and the resultingfluid is at once ready for use. The water content may be varied betweencertain limits depending upon the number of copies it is desired toproduce. I have found, however, that best results are obtained when thewater content is not less than 12% by volume and preferably not over 18%by volume.

A transfer fluid compounded as above will produce a much greater numberof copies than a like quantity of previously known fluids, and thecopies will be more clear and uniform than those heretofore obtainable.The alcohol and water bath act as solvents for the waxes and dyes in thecarbon paper, the water apparently assisting in the wetting andpenetrating action, while the ethylene glycol mono-ethyl ether acts as apenetrating agent and evaporation stabilizer.

While I have described a certain specific embodiment of my invention, Iam aware that many modifications thereof are possible. For example,other alcohols which are substantially non-toxic in character in thevapor state may be used in place of the ethyl alcohol. Also, othersubstituted di-hydric alcohols may be employed in lieu of ethyleneglycol mono-ethyl ether, although the one used should be water soluble.Moreover, it may be found desirable to change the water content,especially where the other ingredients are changed. My invention,therefore, is not to be limited except insofar as is necessitated by theprior art and by the spirit of'the appended claims.

I claim as my invention:

4. A transfer fluid comprising ethyl alcohol,-

ethylene glycol mono-ethyl ether, and water.

5. A transfer fluidcomprising ethyl alcohol, ethylene glycolmono-ethylether, and water, the

water content comprising not less than 12% by v volume.

6. A transfer fluid comprising ethyl alcohol,

ethylene glycol mono-ethyl ether, and water, the

water content comprising not more than 18% by volume.

'7. A transfer fluid comprising ethyl alcohol, ethylene glycolmono-ethyl ether, and water, the water content comprising not less than12% nor more than 18% by volume.

8. A transfer fluid comprising ethyl alcohol, ethylene glycol mono-ethylether, and water, the water content comprising approximately 15% byvolume.

9. A transfer fluid comprising a mono-hydric alcohol approximately byvolume, a Water soluble substituted di-hydric alcohol approximately 60%by volume, and water approximately 15% by volume.

10. A transfer fluid comprising a non-toxic, mono-hydric alcoholapproximately 25% by volume, a water soluble substituted di-hydricalcohol approximately 60% by volume, and water approximately 15% byvolume.

11. A transfer fluid comprising ethyl alcohol approximately 25% byvolume, ethylene glycol mono-ethyl ether approximately 60% by volume,and water approximately l5%' by volume.

PHILIP A. SHILLENN.

